I’ve been doing some more than usual research as of late to answer for myself a specific question about CO2 respiration and the amount of man-made CO2 that is reatined versus naturally generated CO2. In doing so I’ve been in some discussion with some people I share an email list with.
One of them pointed out this ESRL (Earth Systems Research Laboratory) animation to me. I immediately found it intriguing because of the disparity between hemispheres:
CO2 (C13) January 1996 to December, 2007
From ESRL:
This movie shows the latitude distribution (from south-to-north) of average monthly values derived from the GLOBALVIEW extended records. Cyan circles are average monthly values from sampling locations thought to be regionally representative; pluses are average values from locations thought to be influenced by local sources and sinks. A smooth curve is fitted to the representative measurements when sufficient data exist.
Isotopic measurements from NOAA air samples are made by the University of Colorado (CU), Institute of Arctic and Alpine Research (INSTAAR), Stable Isotope Laboratory (SIL).
They caution that this is a derived product, (due to processing, smoothing etc) and does no longer represent raw data on CO2C13, along with other caveats such as this:
These and other measurements have been widely used to constrain atmospheric models that derive plausible source/sink scenarios. Serious obstacles to this approach are the paucity of sampling sites and the lack of temporal continuity among observations from different locations. Consequently, there is the potential for models to misinterpret these spatial and temporal gaps resulting in derived source/sink scenarios that are unduly influenced by the sampling distribution. GLOBALVIEW-CO213 is an attempt to address these issues of temporal discontinuity and data sparseness and is a tool intended for use in carbon cycle modeling.
But still, it is quite informative. Here is a map of the ESRL station distribution. Not all of them are CO2 surface monitoring stations.
Note how the southern hemisphere’s (90S to EQ)CO2C13 content remains nearly steady over the 12 year period, while the northern hemisphere shows major seasonal variation. The greatest variation is at the northernmost latitude, with data that likely comes from the Alert, Nunavut, Canada and the Ny-Alesund, Svalbard ESRL monitoring station.
You can see by the seasonal variation in the movie that when it is warmer, more CO2C13 is being released into the atmosphere, when it is colder, more CO2 C13 is taken out. It demonstrates a short term linkage between CO2 and temperature. While the “paucity of sampling” in the Southern Hemisphere is evident from the map, I find it curious that there is virtually no seasonal variation there, compared to the dance of the datapoints north of the equator, the ones south of the equator are wallflowers.
h/t to Allan Siddons
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“when it is warmer, more CO2C13 is being released into the atmosphere, when it is colder, mores CO2 C13 is taken out.”
That seems backwards. The typical CO2 flux graph show the highest annual CO2 in winter as most vegetation in the higher latitudes go dormant and ice makes impossible the taking of CO2 out of the atmosphere.
Could it be summer soil respiration? I’m not an expert on this, but I wonder if the greater land mass at higher northern latitudes that are exposed during the summer months are putting out more C13 during the summer resulting in higher summer readings?
Could it be the shaking tail in the NH is partly a result of all the SH stations being at or near sea level, whereas many of the NH stations are at much higher elevations?
There is something I mentioned long ago in RC, and can be seen in the graphs. The ammount by which CO2 rises every year is now bigger than it was in the 60’s or earlier. However this is something that affects the winter increase only: the increase from the December (aprox) minimum to the following August (aprox) maximum has been getting bigger and bigger, from about 6.5 ppm in the 60’s to about 8 ppm now. However, the reduction between the August (aprox) maximum to the following December (aprox) minimum has kept quite stable at 6 ppm every year since the 60’s.
Now, we have been increasing our CO2 emissions all year, haven’t we? We should have seen an increase in the winter CO2 release AS WELL AS a reduction in the summer uptake. But the CO2 uptake in the summer is the same as before in spite of us humans emitting a huge ammount of CO2 more in those months than we did in the 60’s.
I posted this in RC as proof of a positive response from Nature to the increase of CO2: plants grow more and uptake more CO2. Plants are mostly in the NH and grow in the summer, so we see the response there. However Gavin Smith told me that I was wrong. We see that in the summer because the Southern Oceans are cold at that time and uptake a lot more CO2, and they uptake more than before because there is more CO2 to uptake. You know, ocean acidification and all that stuff.
However the graph we see here thanks to Anthony proves that wrong. If the main cause for CO2 uptake and release was in the temperature of the Southern Oceans instead of plants respiration, the big seasonal variation should be in the Southern Hemisphere, not in the northern one.
This is also seen in the AIRS animations, in the form of maps.
All that water in the southern hemisphere?
For me it says that the land biomass is breathing hard. The sea biomass is already swimming in a sink/source of CO2, a big buffer, it does not need the heat as the northern hemisphere land mass does to grow. The more north the more the heat is necessary for spring. It is march/april for bloom and absoprption, september october for decay and release.
Pardon, there is a mistake there. I meant increase between October and June, and reduction between June and October. Mistake happened because of the moths I use to detect the ratio of increase and reduction every year. In August I get the maximum minus the minimum of the previous 12 months concentrations to get the winter increase, as it always begins post-August (september or october) and ends before the following august (may or june), and in December I do the oposite to get the reduction.
Why do you find it curious?
Antarctica is a vast very cold continent with little vegetation surrounded by very cold seas and a very stable wind pattern around it to mix atmospheric gasses.
The northern hemisphere contains a lot of land with vegetation the wind patterns are less stable and seasonal temperature variations much larger.
Incidentally this hemispheric pattern shows up well on the Airs satellite photos. Note the high level of CO2 in the tropical regions.
Which only goes to show it is unwise to think that the proportion of CO2 is either a constant throughout the atmosphere and indeed throughout the year: or that Antarctica is a very good place to sample ice cores and deduce past climate either in the northern hemisphere or indeed over much of the globe.
Antarctica has a climate all its own.
Kindest Regards
This figure seems to be a new way to visualize the annual variation of CO2 content, as seen, e.g. in the oscillations of the Mauna Loa data. There is a winter peak and a summer minimum, explainable by heating and plant growth on the land masses of the Northern Hemisphere. In comparison, population in those parts of the Southern Hemisphere, which lie in latitudes south of the tropic of capricorn, is relatively low, since the land area there is quite small compared to NH.
Anthony,
You haven’t given much emphasis to the fact that these are Carbon-13 ratio numbers, not raw CO2. They are intended to track CO2 of fossil fuel origin. That’s the main reason for the hemisphere imbalance.
REPLY: I mentioned CO2C13 seven times in the post. It seems enough. – Anthony
Glenn,
“Could it be the shaking tail in the NH is partly a result of all the SH stations being at or near sea level, whereas many of the NH stations are at much higher elevations?”
You have identified one, of many, problems associated with sampling, something the mining industry had to come to grips with last century when estimating mineral ore reserves, (figuring exactly how much metal is in an orebody from a minimum number of samples without making too much of a stuff up. Steve McIntyre might add to this).
It’s basically what we describe as sample support and related to the statiscal sin of mixing oranges and apples.
Firstly it requires a good understanding of the physical structure of the object being sampled. In this case the chemical composition of the atmosphere vs. height, hence your question.
You have identified another climatic minefield with your innocent question.
🙂
Questions (and I hope they are not too dumb).
1. Isn’t the dC13CO2 (ratio) supposed to somehow be indicative of anthropogenic (fossil) CO2 vs. “natural” C02?
2. Isn’t the thinking that the more negative that dC13C02 is, the more anthro the CO2 is?
3. The most negative states appear to be in the NH in winter/spring (~May), and the least negative in the NH again in summer/fall (~Sept). What does that indicate about anthro vs natural CO2 emissions?
Sorry if these questions are too uneducated.
I wonder if we are seeing a second-order effect and not a reflection of the actual CO2 concentration? These data refer to the C13 isotope. Could it be that its the ratio C12/C13 that’s changing over the seasons which we see here?
What about this: suppose fossil fuel carbon has a lower C13 fraction than in the biosphere (because its has been burried for a long time and is depleted by decay?). If you burn it predominatly in winter you would expect a slightly lower C13 fraction compared with summer, in particular around Northern lattitudes 30-50 where most of the production is.
Anybody know any data to support or refute this idea? e.g. what exactly is the C13 content of fossil carbon in coal or natural gas?
Further to my earlier entry, I found this url, which may explain it.
http://cat.inist.fr/?aModele=afficheN&cpsidt=16626035
Any global warming caused by 350ppm CO2 in the air pales into insignificance compared with that produced by moisture. Yet even Al Gore et al does not refer to moisture as a GHG.
Plants preferentially take up C12. The vast majority of the Earth’s vegetation is in the northern hemisphere. Thus, during the northern hemisphere summer, a lot of CO2 is being removed from the atmosphere, and more of it has a C12 molecule than a C13 molecule. Hence the seasonal drop in C13 in the northern hemisphere but little variation in the south.
Fossil fuels are ex-plants. Thus, they contain more C12 than C13 in their carbon-based molecules. Thus, by burning them and releasing a large quantity of CO2, we are causing the atmosphere to contain less C13 than it otherwise would.
So, when looking at the isotopes, you see that there is a long-term downward trend in δC13, and superimposed on that is an annual cycle.
This is a great animation showing that northern hemisphere vegetation controls the up and down seasonal cycle of CO2.
The oceans wouldn’t provide such a signal even though they also oscillate with the seasons since the southern ocean also warms and cools with the seasons and there is no signal there.
It is a little curious the northern hemisphere seasonal signal varies more as you go north whereas one would expect the max seasonal signal to be in the mid-northern-latitudes (where there is greater growth and die-off of plants with the season). But the signal seems to vary more as you go progressively farther north.
We also know that the temperatures affect the annual growth rate of CO2 (by as much as +/-50%). I think we have to conclude this is due to the vegetative response rather than the oceans.
This would also indicate that northern hemipshere CO2 sinks provided through vegetation (forests and pastureland) will grow progressively more effective as global warming temperatures rise (slightly). There was a study out last week that showed tropical forests are sinking/growing more rapidly with the slightly warmer world.
Regarding my comments above about the CO2 sinks and warmer conditions, I think I have to pull those comments since it is not clear enough right now to say that. Sorry.
Rachel (03:22:35) : Plants preferentially take up C12.
Thank you,
I did not know that but I was actually wondering about it the other day (God knows why). I just googled it and came up with Kinetic isotope effect.
That was NOT covered in my two freshman chemistry classes at Georgia Tech in 1974.
Rachel (03:22:35) : The vast majority of the Earth’s vegetation is in the northern hemisphere.
I’m wondering about this. There is an awful lot of algae in the ocean.
It struck me odd that the X-axis is sin(lat) instead of just the latitude, then I realized it adjusts for the declining land area of bands of latitude as you head away from the equator. For those of us living near latitude 45, we show up at sin(+/-45) = +/-0.7.
Good confirmation that CO2 solubility in water drops off quickly as temperatures rise above 0C.
http://wattsupwiththat.files.wordpress.com/2008/04/co2_solubility_h2o.jpg?w=516&h=386
As explained here:
http://wattsupwiththat.com/2009/02/20/basic-geology-part-2-co2-in-the-atmosphere-and-ocean/
Interesting post, it says something about the well mixed assumptions in at least some models. The satellite crash the other day was really bad news, It would have gone a long way to understanding the magnitude of sources and sinks just by it’s area of coverage. I wonder if the JAXA version has similar capabilities.
Working on the antarctic paper, I did a plot last night which shows how the spatial weighting of surface station data by RegEM was not maintained for calculation of trend. It looks like a pretty big issue to me.
http://noconsensus.wordpress.com/2009/02/25/correlation-of-reconstructions/
R Stevenson,
Water vapor is indeed a GHG, but is not mentioned because it is a feedback — it cannot CAUSE a change in climate. It has a very short atmospheric lifetime (about a week), compared to CO2 (around 250 years). CO2 that ends up in the atmosphere stays there for a long time, while water vapor in the atmosphere quickly condenses as temperatures drop. Then, when temperatures rise again, water quickly evaporates.
So, it is true that water vapor makes the largest contribution to the TOTAL greenhouse effect, but it cannot create a CHANGE in the effect. It only amplifies the changes created by other forcings, such as CO2, methane, the Sun, etc.
Perhaps this guest post by Dr. Spencer last year on the C13/C12 ratio might be of interest to readers of this current post:
http://wattsupwiththat.com/2008/01/28/spencer-pt2-more-co2-peculiarities-the-c13c12-isotope-ratio/
Rachel says:
Bingo…And, I might add that while eventually the CO2 gets to be pretty well-mixed throughout the globe, this takes a while…particularly to mix between the two hemispheres…so that these shorter timescale oscillations are seen.
The sky is falling:
http://www.sciencedaily.com/releases/2008/02/080229075228.htm
Evacuate the coastal areas immediately.
off topic.There is an interesting article at The Register about a new Japanese break with IPCC views on climate http://www.theregister.co.uk/2009/02/25/jstor_climate_report_translation/